Cryogenic refrigerator including separating device

ABSTRACT

A cryogenic refrigerator has a separating device provided between a lower temperature portion and a heat exchanger to selectively separate the lower temperature portion and the heat exchanger, and thus to selectively block heat transfer between the lower temperature portion and the heat exchanger. According to the cryogenic refrigerator, it can have an ability to perform a maintenance operation of the cryogenic refrigerator at normal temperature by blocking heat transfer from the lower temperature portion to the heat exchanger during maintenance after disassembly.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Korean Patent Application No. 10-2005-91824, filed on Sep. 30, 2005, in the Korean Intellectual Property Office, the disclosure of which incorporated herein in its entirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the invention

The present invention relates to a cryogenic refrigerator including a separating device, and more particularly to a cryogenic refrigerator including a separating device provided between a lower temperature portion and a heat exchanger for selectively blocking heat transfer between the lower temperature portion and the heat exchanger by the separating device, during maintenance.

2. Description of the Prior Art

Typically, there is a need for a cryogenic environment in a variety of fields including high vacuum related industries, energy related industries, medical industries, transportation related industries, food industries, aerospace industries, telecommunication industries, etc, and its practical applications have been increasingly expanded as technology in these fields develops.

Refrigeration technology is that it liquefies nitrogen, argon, helium, etc, circulates and stores these liquefied liquids in any suitable ways, cyclically delivers them to a place in which refrigeration is required, and thus achieves a cryogenic environment. Cryogenic refrigerator is divided into two regions; a closed system region for liquid nitrogen coolant(hereinafter referred to a heat exchanger), which has a relatively high temperature range of 76-77K, and a closed system region for liquid helium coolant(hereinafter referred to a lower temperature portion), which has a relatively low temperature range of about 4.2K very close to 0k. Recently, cryogenic refrigerator combining these two coolant regions is used. Although not shown in Figs, the above-mentioned lower temperature portion and heat exchanger have their own coolant inlet port and coolant outlet port.

According to the above-mentioned cryogenic refrigerator construction, heat is transferred from the heat exchanger to the lower temperature portion depending upon a temperature gradient. However, in order to perform a maintenance operation for the cryogenic refrigerator comprised of the lower temperature portion and the heat exchanger, it is necessary to disassemble the lower temperature portion which is adjacent to a body section, and while performing a maintenance operation after the disassembly, the temperature of the lower temperature portion is raised to cause the temperature gradient to go into reverse, and thus there is involved a problem that heat is transferred from the lower temperature portion to the heat exchanger being directly contacted with an article to be refrigerated.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been made to solve the above-mentioned problems, and an object of the invention is to provide a cryogenic refrigerator capable of preventing heat transfer from the lower temperature portion to the heat exchanger, during a maintenance operation of the cryogenic refrigerator.

The above object of the present invention is achieved by a cryogenic refrigerator comprising a lower temperature portion, a heat exchanger, and a separating device provided between the lower temperature portion and the heat exchanger to selectively separate the lower temperature portion and the heat exchanger, and thus to selectively block heat transfer between the lower temperature portion and the heat exchanger.

Here, the separating device may include an upper plate; a lower plate having a shape corresponding to that of the upper plate; side plates connecting the upper plate and the lower plate to form a cavity portion therein; and a conduit supplying gas to the cavity portion or discharging the gas from the cavity portion, and when the gas is supplied to the cavity portion, the separating device is expanded to separate the upper plate and the lower plate away from each other, and thus to block the heat transfer between the lower temperature portion and the heat exchanger, and when the gas is discharged from the cavity portion, the separating device is contracted to closely contact the upper plate with the lower plate toward each other, and thus to permit the heat transfer between the lower temperature portion and the heat exchanger.

According to the present invention, the separating device may be comprised of aluminum, copper, stainless steel, or oxygen-free copper, and the gas supplied to the cavity portion may consist of nitrogen, helium, or argon.

Meanwhile, according to the invention, an adhesive layer may be applied onto opposite faces of the upper plate and the lower plate of the separating device, thereby easily keeping a close contact state of the upper plate and the lower plate upon contracting of the separating device.

Here, the adhesive layer may consist of indium.

Meanwhile, according to the present invention, the separating device may include two or more conduits adapted for supplying the gas into the cavity portion or discharging the gas from the cavity portion.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a front view of a cryogenic refrigerator including a separating device according to a preferred embodiment of the present invention, showing a state in which the cryogenic refrigeration operates while the separating device is contracted;

FIG. 2 is a top plan view of the separating device in FIG. 1;

FIG. 3 is a cross-sectional view taken along the line III-III′ of FIG. 2;

FIG. 4 is a front view of a cryogenic refrigerator being in a maintenance state while the separating device of FIG. 1 is expanded;

FIG. 5 is a front view of a cryogenic refrigerator including a separating device according to another preferred embodiment of the present invention, showing a state in which the cryogenic refrigeration operates while the separating device is contracted;

FIG. 6 is a top plan view of the separating device in FIG. 5; and

FIG. 7 is a front view of a cryogenic refrigerator being in a maintenance state while the separating device of FIG. 5 is expanded.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a cryogenic refrigerator according to preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, in which

FIG. 1 is a front view of a cryogenic refrigerator including a separating device according to a preferred embodiment of the present invention, showing a state in which the cryogenic refrigeration operates while the separating device is contracted.

Referring to FIG. 1, the cryogenic refrigerator 100 according to the present invention includes a body portion 10 supported by a hanger 11, a lower temperature portion 1 and a heat exchanger 2 successively provided on a lower portion of the body portion 10, and a separating device 3 provided between the lower temperature portion 1 and the heat exchanger 2.

The body portion 10 is supported by the hanger 11, and the heat exchanger 2 which contacts with both the lower temperature portion 1 and an article being refrigerated to perform heat exchange therebetween, is provided on the lower portion of the body portion.

The heat exchanger 2 is supported by a support bar 5 extending downward from the hanger 11, a buffer 15 with one end connected to the lower portion of the support bar 5, and an auxiliary support bar 16 connected to the other end of the buffer 15. Since the cryogenic refrigerator 100 is operated through repeated operations of an adiabatic expansion process, an oscillation is occurred in the heat exchanger, and the buffer 15 provided between the support bar 5 and the auxiliary support bar 16 absorbs and reduces the oscillation. As this buffer 15, a variety of buffers are already known, and the present invention preferably employed a spring as a buffer.

The separating device 3 is installed between the heat exchanger 2 and the lower temperature portion 1. The separating device 3 is selectively contracted and expanded to block or permit heat transfer between the heat exchanger 2 and the lower temperature portion 1. This separating device 3 is illustrated in detail in FIG. 2 and FIG. 3.

FIG. 2 is a top plan view of the separating device 3 of the cryogenic refrigerator 100 according to the present invention, and FIG. 3 is a cross-sectional view taken along the line III-III′ of FIG. 2.

Referring to FIG. 2 and FIG. 3, the separating device 3 includes an upper plate 6, a lower plate 8 having a shape corresponding to that of the upper plate 6, and side plates 7 connecting the upper plate 6 and the lower plate 8 to form a cavity portion 20 therein.

The upper plate 6 and the lower plate 8 preferably have a circular shape, and have corresponding size. The side plates 7 connecting the upper plate 6 and the lower plate 8 has a ‘C’-shaped or ‘<’-shaped cross-section, thereby forming the cavity portion 20 by the upper plate 6, the lower plate 8 and the side plates 7. The upper plate 6 and the lower plate 8 have a deformable structure which deforms about the side plates, for example, flexes about the side plates 7, so that it allows the upper plate and the lower plate to close contact toward each other or separate away from each other. Preferably, the upper plate 6, the lower plate 8 and the side plates 7 are comprised of any one of aluminum, copper, stainless steel, or oxygen-free copper.

In addition, an adhesive layer 9 is applied onto opposite faces of the upper plate 6 and the lower plate 8, and aids to easily keep close contact state when the upper plate 6 and the lower plate 8 closely contact to each other. The material of the adhesive layer 9 is particularly limited, but preferably the present invention employs indium as the material of adhesive layer.

A conduit 4 is connected to one side of the upper plate 6, and supplies gas into the cavity portion 20 for expanding the separating device 3, or discharges the gas from the cavity portion 20 for contracting the separating device 3. The conduit 4 is connected to an external gas supply device, not shown in FIGS. Preferably, the gas may consist of nitrogen, helium, or argon.

Now, the operation of the separating device 3 used in the cryogenic refrigerator 100 of the present invention will be described. When gas is supplied from the external gas supply device through the conduit 4 into the cavity portion 20 of the separation device 3, the separating device 3 is expanded by pressure of the gas, thereby separating the upper plate 6 and the lower plate 8 away from each other. On the contrary, when the gas is discharged from the cavity portion 20 of the separating device 3 through the conduit 4, the separating device 3 is contracted to force the upper plate 6 and the lower plate 8 to close contact toward each other. As the upper plate 6 and the lower plate 8 is closely contacted to each other, an adhered layer 9 applied onto opposite faces of the upper plate 6 and the lower plate 8 further facilitate the close contact therebetween.

FIG. 4 is a front view of a state in which the separating device 3 is expanded by gas supplied thereinto.

As shown in FIG. 4, if it is necessary to perform a maintenance operation for the cryogenic refrigerator 100, operator supplies gas into the cavity portion 20 of the separating device 3 to expand the separating device 3. By this operation, the upper plate 6 (FIG. 3) and lower plate 8 (FIG. 3) of the separating device 3 are spaced away from each other to block heat transfer between the lower temperature portion 1 and the heat exchanger 2, and accordingly, even if the temperature of the lower temperature portion 1 temporarily raises, the heat transfer from the lower temperature portion 1 to the heat exchanger 2 is prevented.

On the contrary, when the operator intends to operate again the cryogenic refrigerator 100 after the maintenance operation is finished, the operator, as shown in FIG. 1, discharges the gas from the cavity portion 20 through the conduit 4 to contract the separating device 3. The upper plate 6 and the lower plate 8 are closely contacted to each other by the contraction of the separating device 3, and are easily closely contacted to each other by an adhesive layer 9 applied onto opposite faces of the upper plate 6 and the lower plate 8. Heat transfer is occurred by means of the close contact between the upper plate 6 and the lower plate 8, and thus the cryogenic refrigerator 100 is operated again.

FIG. 5 is a front view of a cryogenic refrigerator 100′ according to another preferred embodiment of the present invention, showing a state in which the cryogenic refrigeration 100′ operates while the separating device 3′ is contracted.

Referring to FIG. 5, the embodiment of FIG. 5 is different from the embodiment of FIG. 1 in that there is installed two or more conduits 4, 4′ connected to the separating device 3′, through which gas is supplied into or discharged from the separating device 3′. Below, the difference between the embodiments of FIG. 1 and FIG. 5 will be described in detail.

FIG. 6 is a top plan view of the separating device 3′ according to the present embodiment. Referring to FIG. 6, in the separating device 3′ according to the present invention, two conduits 4, 4′ are symmetrically provided at both sides about the lower temperature portion 1. Although only two conduits 4, 4′ are shown in FIG. 6, the present invention is not limited to that, but may include any suitable number of conduits more than two.

FIG. 7 is a front view of a cryogenic refrigerator 100′ including a separating device 3′ being in a maintenance state while the separating device is expanded.

Now, referring to FIG. 5 and FIG. 7, the operation of the separating device 3′ of the cryogenic refrigerator 100′ according to the present embodiment will be described.

As shown in FIG. 5, when the cryogenic refrigerator 100′ is operated, the conduit 4 on one side is closed, the conduit 4′ on the other side is opened, and gas is discharged from the cavity portion 20 through the opened conduit 4′ to contract the separating device 3′. The upper plate 6 and the lower plate 8 are closely contacted to each other by the contraction of the separating device 3′, and are easily closely contacted to each other by an adhered layer 9 applied onto opposite faces of the upper plate 6 and the lower plate 8. Heat transfer between the lower temperature portion and the heat exchanger occurs by close contact between the upper plate 6 and the lower plate 8 to operate the cryogenic refrigerator 100′.

On the contrary, as shown in FIG. 7, when it is necessary to perform a maintenance operation for the cryogenic refrigerator 100′, operator supplies gas into the cavity portion 20 of the separating device 3′ to expand the separating device 3′. Specifically, the operator supplies gas through the conduit 4 on one side into the cavity portion 20 of the separating device 3′ to expand the separating device 3′, and then discharges the gas through the conduit 4′ on the other side. In this case, the gas is discharged through conduit 4′ on the other side while maintaining the volume of the gas within the cavity portion 20 at a desirable amount for keeping the expanded state of the separating device 3′. The upper plate 6 and the lower plate 8 are spaced away from each other by expansion of the separating device 3′, and thus heat transfer between the lower temperature portion 1 and the heat exchanger 2 is blocked, so that heat is not transferred from the lower temperature portion 1 to the heat exchanger 2, even if the temperature of the lower temperature portion 1 temporarily raises during maintenance.

According to this embodiment, if it is necessary to expand the separating device 3′, gas is successively supplied through conduit 4 on one side, and is discharged through the conduit 4′ on the other side while maintaining the volume of the gas within the separating device 3′ at a desirable amount. Accordingly, as gas within the cavity portion 20 is condensed by the heat exchanger 2 of lower temperature connected to the lower plate 8, so as to decrease the volume thereof is decreased, thus it is not possible to keep the expanded state of the separating device 3′. Consequently, it is prevented the upper plate 6 and the lower plate from closely contacting to each other.

According to the present invention, a cryogenic refrigerator including a separating device provided between a lower temperature portion and a heat exchanger can have an ability to perform a maintenance operation of the cryogenic refrigerator at normal temperature, by selectively blocking heat transfer between the lower temperature portion and the heat exchanger by the separating device, during maintenance.

Although preferred embodiments of the present invention have been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. 

1. A cryogenic refrigerator comprising: a lower temperature portion; a heat exchanger; and a separating device provided between the lower temperature portion and the heat exchanger to selectively separate the lower temperature portion and the heat exchanger, and thus to selectively block heat transfer between the lower temperature portion and the heat exchanger.
 2. The cryogenic refrigerator as claimed in claim 1, wherein the separating device includes an upper plate; a lower plate having a shape corresponding to that of the upper plate; side plates connecting the upper plate and the lower plate to form a cavity portion therein; and a conduit supplying gas into or discharging gas from the cavity portion, wherein, when the gas is supplied into the cavity portion, the separating device is expanded to separate the upper plate and the lower plate away from each other, and thus to block the heat transfer between the lower temperature portion and the heat exchanger, and when the gas is discharged from the cavity portion, the separating device is contracted to closely contact the upper plate with the lower plate toward each other, and thus to permit the heat transfer between the lower temperature portion and the heat exchanger.
 3. The cryogenic refrigerator as claimed in claim 2, wherein the separating device is made from aluminum, copper, stainless steel, or oxygen-free copper.
 4. The cryogenic refrigerator as claimed in claim 2, wherein the gas supplied into the cavity portion consists of nitrogen, helium, or argon.
 5. The cryogenic refrigerator as claimed in claim 2, wherein an adhesive layer is applied onto opposite faces of the upper plate and the lower plate of the separating device.
 6. The cryogenic refrigerator as claimed in claim 5, wherein the adhesive layer consists of indium.
 7. The cryogenic refrigerator as claimed in claim 2, wherein the separating device includes two or more conduits adapted for supplying the gas into or discharging the gas from the cavity portion. 